Electromagnetic control switch



Oct. 7, 1947. c. c. WHITTAKER ELECTROMAGNETIC CONTROL SWITCH Filed July 7. 1944 l N V EN TO R Cfv lea 6. Wkly/draft WITNESSES:

ATTORNEY Patented Oct. 7, 1947 ELECTROMAGNETIC CONTROL SWITCH Charles C. Whittaker, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 7, 1944, Serial No. 543,896

My invention relates to electromagnetic contactors and aims at providing a switch especially suited for temporary high duty operation such as required for energizing a propulsion or other electric drive by battery current for a limited period of current flow.

According to the invention, such a switch is provided with latch means which lock a main contact in circuit-closing position and which, upon electromagnetic release, lock the contact also in the circuit-opening position so that a resetting operation has to be performed by the operator before the switch is ready for another control operation. According to another feature of the invention, the control circuit of the electromagnetic means for moving the latch into contact releasing position extends through an interrupter contact which is controlled by the latch so that the electromagnetic means become deenergized when the main contact has opened and cannot be re-energized before the main contact is normally re-closed.

These and other features of the invention will be apparent from the embodiment illustrated in the drawing, in which:

Figure 1 is a part sectional front view of an electromagnetic contactor;

Fig. 2 is a side elevation of the same contactor;

Fig. 3 represents another side elevation seen from the side opposite to the viewpoint of Fig. 2;

Fig. 4 shows another front view similar to that of Fig. 1, but representing the switch contact in the circuit-opening position; and 1 Fig. 5 is a circuit diagram relating to the switch structure according to Figs. 1 through 4.

The electromagnetic switch, according to the drawing, has a supporting base plate I. An angular bracket 2 of a highly conductive material is mounted on base plate I and carries a terminal screw 3. A bar-shaped main contact arm 4 is pivoted, about a pin 5 to the bracket 2 so as to be capable of angular movement from the contact-closing position shown in Fig. 1 to the opening position shown in Fig. 4. A flexible shunt 5a connects bracket 2 with arm 4. The contact arm 4 is provided with a contact 6 for engaging a stationary contact I. Contact I is attached to an angular bracket 8 which is firmly secured to the base plate I and carries a terminal screw 9 and a resiliently mounted arcing contact I0 for engaging the end portion of contact arm 4. A helical compression spring II extending between the arm 4 and an angular abutment I2 attached to the base plate I biases arm 4 toward its opening position.

A leaf spring I3, also pivoted for motion about 2 Claims. (Cl. 200-406) pin 5, extends along contact arm 4 and has a slot I4 at its free end. A locking projection I 5 formed of an angular metal piece is secured to spring I3 for. cooperation with a movable latch I6. This latch is mounted on a leaf spring 25, which, in turn, is secured to a sleeve 26 revolvably mounted on a pin IT. The latch I6 has a slanted surface at I8 and a nose at I9. A helical spring 21 seated on sleeve 26 tends to hold the latch I6 in the operative locking position shown in Fig. 1. In this position, the nose I9 of latch I6 abuts against the projection I5, and thereby retains leaf spring l3 and contact arm 4 in the contact-closing position against the bias of spring II and under resilient deflection of arcing contact It.

An insulator 20 mounted on leaf spring 25 carries an auxiliary contact 2| for engaging a stationary contact 22 mounted on a bracket 23 which carries a terminal screw 24. Contacts 2I and 22 engage each other when the latch I6, under the bias of spring 21, maintains its operative locking position according to Fig. 1, but are separated when the latch I6 is forced in the counterclockwise direction about the pivot pin Il by the electromagnetic means to be described presently.

A magnet coil 30 surrounding a non-magnetic guiding sleeve 3| is attached to the base plate I by means of plates 28 and 29. A magnetizable plunger core 32 is axially displaceable within sleeve 3| and biased by a helical compression spring 33 which tends to hold the core 32 against a stationary abutment 34. A non-magnetic pin 35 is attached to core 32 and extends through the core of a magnetic core portion 36 which is stationarily mounted in sleeve 3|. The energizing circuit for coil 30 extends from terminal 3 through conductors 31' and 38 to the movable contact 2| of the latch assembly.

This circuit is more clearly apparent from the diagram of Fig. 5. According to Fig. 5, the main circuit to be controlled, for instance, the motor circuit of the propulsion drive for a practice torpedo, extends between terminals 3 I and 9 through contact arm 4. The control circuit for coil 30 extends through elements 3, 3|], 2|, 22, and 23 to a control contact C which does not form part of the electromagnetic switch proper but is actuated by a separate timing mechanism (not shown).

' When latch I6 and the main contact assembly of the switch are latched in the position shown in Fig. 1, the circuit is in the operative condition represented by Fig. 5. The current through terminals 3 and 9, passing through the main contact assembly, is switched in together with the timing 3 mechanism that controls the contact C. If the timing mechanism is set, for instance, for three minutes, the contact C is closed upon elapse of this period. The closure of contact C passes energizing current through coil 30 so that the movable core 32 is shifted against the force of spring 33 until pin 35 hits against latch I6 and turns it counterclockwise in opposition to spring 21.

This-releases the nose l5 so that leaf spring I:

and contact arm 4 are free to follow the bias of spring ll. placed into the position shown in Fig. 4. During the opening motion of arm 4, the engagement between contacts 6 and I is interrupted before the interruption occurs between the flexible arcing contact in and the appertaining portion of arm 4. Hence, the interrupting duty is assigned to the arcing contact In whose material is especially chosen for this purpose, while the current-carrying duty during the closing period is performed by the more highly conductive con tacts 6 and I.

During the movement of the latch from the position of Fig. 1 to that of Fig. 4, the engagement between contacts 2| and 22 is interrupted and thereby the coil 30 deenergized. At the end of the circuit-closing operation, as represented in Fig. 4, the slot I4 has moved toward the pivot axis of latch l6, and the slanted surface l8 of the latch has slid over the bottom of the slot ll. When the interrupting operation of the main circuit and the coil circuit is completed, the leaf spring 13 prevents the latch 16 from moving back into its original position. Consequently, the switch is safely latched in its open position so that neither the main circuit nor the coil circuit can be reclosed before the arm 4 is reset into its original position, and this has to be done by the operator. In this manner, the switch affords a safe control of heavy current loads, for instance, in the order of magnitude of 2,000 amperes, for operating periods of several minutes. The switch has the further advantage that it is suitable for such heavy duty operation while requiring comparatively little space. The energizing coil 30 need be rated only for intermittent operation because its circuit is always interrupted shortly after its closure. Such rating contributes also to reducing the space requirements of the apparatus; it permits further to impart very strong forces to the movable core 32 and to the springbiased latch mechanism, thereby improving the safety of operation. As a further result, the core portion 32 and the appertaining biasing spring 33 can be dimensioned so as to remain non-responsive to moving forces of lesser magnitude such as occurring during acceleration periods of torpedoes.

It will be understood by those skilled in the art that contact apparatus according to the inven- As a result, the switch elements are 4 tion can be modified as to details without departing from the gist and essential features of the invention as set forth in the claims attached hereto.

I claim as my invention:

1. A switch comprising a main contact assembly movable between opening and closing position and biased towardopening position, a movable latch biased toward a position where it holds said assembly in said closing position in opposition to the assembly bias, an electromagnet having armature means biased toward inoperative position and a. coil for causing, when energized, said means to entrain said latch against the latch bias thereby releasing said assembly for circuitopening motion, contact means controlled by said latch and connected with said coil for deepergizingit upon release operation of said latch so asto cause said armature to return to its inoperative position under said armature bias, said latch and said assembl forming an interlock so that said latch is held by said assembly against said latch bias in order to maintain said contact means in coil deenergizing position after the release of said assembly whereby said coil becomes operative only after resetting of said assembly.

2. A switch comprising a main contact assembly movable between opening and closing positions and biased toward opening position, said assembly comprising a heavy duty contact bar with an arcing contact, a coiled biasing spring tending to open said contact, and a leaf spring disposed opposite said coiled spring for holding said bar against said tendency when stressed, a latch movable between latching and releasing positions and biased toward said releasing position for holding said leaf spring in stressed condition, said latch and said leaf spring having mutuall interlocking stops so that said latch is locked against said latch bias in said releasing position after a release of said leaf spring and bar so as to require resetting of said assembly before returning into said latching position, electric control means for releasing said latch, and contact means controlled by said latch and connected with said control means for rendering said control means inoperative when said latch is in said releasing position.

CHARLES C. WHITTAKER.

REFERENCES CITED The following references are of record in the file of this patent: 

